I am reminded of the battle at Helm's Deep from The Lord of the Rings.  There are only two other cinematic scenes that come close: the gun battle in downtown Los Angeles in Heat and the taking of the beaches in Saving Private Ryan.  Helm's Deep is probably one of the greatest war scenes in all of movie-making history.

Backs against the wall, Théoden's forces were faced with an existential threat of wave after wave of never-ending combatants who laid siege to the wall.

The Deeping Wall protects the Deep behind the Keep, this is the only escape for the Defenders.

Sauron knew that if the wall was breached, then his invading forces could take the Hornburg.  Better, then, would be to keep one's main focus on the wall. 

The tactical importance of walls should seem obvious.  Even Sun Tzu wrote about the exhaustion of trying to overcome walls:

Thus the highest form of generalship is to balk the enemy's plans; the next best is to prevent the junction of the enemy's forces; the next in order is to attack the enemy's army in the field; and the worst policy of all is to besiege walled cities.

They should be avoided at all cost. 

And here again:

The rule is, not to besiege walled cities if it can possibly be avoided.  The preparation of mantlets, movable shelters, and various implements of war, will take up three whole months; and the piling up of mounds over against the walls will take three months more.

Laying siege to walled cities is costly.  And while natural barriers like rivers, cliffs, and mountains are good, well constructed ramparts are nearly impossible to defeat.

In Nehemiah, we read that the returned exiles after rebuilding the temple at Jerusalem needed a wall for protection.  Without a wall, they were vulnerable to foreign invaders, wild animals, or any other unwanted or unvetted source that could cause havoc with the people in the city.

Without walls, there is vulnerability.  Well fortified cities are prosperous cities.  Broken down walls represent nakedness and shame.  In the Old Testament, we find that walls represent holiness and protection and provide structure for society.  Walls were a sign of God's blessing and provision for his people.

Nehemiah was attacked the very instant he decided to put the first brick into place.  Sanballat, Tobiah, the Arabs, and the Ammonites mocked and ridiculed him, relentlessly attacking day and night.  They sounded like Democrats, who trot out memes about "walls don't work" and "a 10-foot wall is defeated by an 11-foot ladder."

Here we read in Nehemiah 4:3:

Tobiah the Ammonite, who was at his side, said, "What they are building – even a fox climbing up on it would break down their wall of stones!"

Sound familiar?  The Democratic Party has literally become toxic to the United States of America and her citizens.  The Democrats' gangrenous rhetoric originates from a slow realization of their own increasing irrelevance with the American people.

They have aligned themselves with the only viable strategy left: encourage illegal entry.  Get as many on amnesty and social assistance as possible as fast as you can, and begin systematically mining them for power.

Meanwhile the Census records the number of people living in each county, which is how representation is scored.  This is what many people don't seem to understand.  When it comes to reapportionment, it's not even necessarily illegal voting that is the concern, although it also can be.  By even just tolerating illegal immigration into the U.S., House seats are affected through redistribution.  The U.S. Census counts people here even on a temporary status, and seats will be apportioned based on their presence.  This has an effect on each state that is larger than many realize.

Also, once the first wave is here, those born here afterward instantly become citizens.  It is automatic.  And since the birth rates of both Central Americans and Mexicans are higher than practically every other demographic group, their political power is growing exponentially compared to current citizens.

And since over 60% of illegal aliens are on some form of welfare (worse, after ten years, it becomes over 70%!), guess whom they vote for after they are institutionalized by their masters. 

The Democrats are like a dying patient who constantly needs a new blood transfusion to stay alive.  Like a vampire, they must continually get new recruits or face extinction. 

Like Sauron, they know that the way in is through the wall.  Like those who ridiculed Nehemiah, they know that if they can mock and stall and shut down the government long enough, they may be able to keep a wall from being raised, since a wall represents their extinction as a party.